Flip-chip light-emitting device with micro-reflector

ABSTRACT

A Flip-chip light-emitting device with integral micro-reflector. The flip-chip light-emitting device emits reflected light provided by a light-emitting layer. The micro-reflector reflects light that might otherwise be lost to internal refraction and absorption, so as to increase light-emitting efficiency.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a division of applicant's earlier application, Ser. No. 10/906,572, filed Feb. 24, 2005, the entirety of which is incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention provides a light-emitting device, and more particularly, a flip-chip light-emitting device with a micro-reflector.

2. Description of the Prior Art

The applications of light-emitting diodes include optical display devices, traffic signals, data storing devices, communication devices, illumination devices, and medical apparatuses, and are getting more extensive. Therefore it is important to increase the brightness of light-emitting diodes, and to simplify manufacturing processes in order to decrease the cost of the light-emitting diode.

Please refer to FIG. 1, which is a schematic diagram of a flip-chip light-emitting device and its related method of manufacture disclosed in TW patent 441859, in which a first electrode and a second electrode of the flip-chip light-emitting device emit reflected light out from a light-emitting layer. However, due to the reason that only light emitted at an angle within the critical angle θc would be completely emitted out, and other light would be reflected and absorbed, the device showed in FIG. 1 has a limited viewing angle and a readily identifiable source of inefficiency in the form of internal absorption of emitted light. In other words, the angle of light of the flip-chip light-emitting device must be within a cone of 2θc to be completely emitted out. Light emitted at an angle larger than 2θc is reflected and absorbed. When light generated within the flip-chip light-emitting device travels from a material with a high refractive index to a material with a low refractive index, the angle of light emitted is limited due to the effect of the refractive indexes. Therefore, with respect to both viewing angle and intensity, how to improve the efficiency of light emission becomes an important issue.

SUMMARY OF THE INVENTION

The claimed invention provides a flip-chip light-emitting device with a micro-reflector. The micro-reflector includes a transparent patterned light-emitting stack layer, and a reflective layer formed over the transparent patterned light-emitting stack layer. The transparent patterned light-emitting stack layer and the transparent patterned layer may be formed into a variety of shapes, including semicircular, pyramidical, conical, and so on, and can be continuous or discontinuous. The transparent patterned light-emitting stack layer generated by means of etching on a light-emitting stack layer of the flip-chip light-emitting device, of evaporation deposition, or of a bonding method. The reflective layer is formed over the transparent patterned light-emitting stack layer by means of evaporation deposition, so that the reflective layer includes the specific shapes to form a micro-reflector. The micro-reflector reflects vertical light with incoming light provided by a light-emitting area, so that the normal incidence light is unaffected by the critical angle for improving light extraction.

The claimed invention provides another flip-chip light-emitting device with a micro-reflector. The micro-reflector includes a transparent patterned layer. The transparent patterned layer generated by means of etching on a semiconductor layer of the flip-chip light-emitting device, of evaporation deposition, or of a bonding method. Then the reflective layer is formed over the transparent patterned layer, so that the reflective layer includes the transparent patterned shapes to form a micro-reflector.

Briefly described, the claimed invention discloses a flip-chip light-emitting device with a micro-reflector. The flip-chip light-emitting device with a micro-reflector includes a substrate, a first semiconductor stack layer formed over the substrate with a first surface and a second surface, a light-emitting layer formed over the first surface, a second semiconductor stack layer formed over the light-emitting layer, a micro-reflector formed over the second semiconductor stack layer with a transparent patterned layer and a reflective layer forming over the transparent patterned layer, a first electrode formed over the micro-reflector, and a second electrode formed over the second surface.

The substrate comprises at least one material selected from a material group consisting of GaP, glass, SiC, GaN, ZnSe, and sapphire, or other substitute materials. The reflective layer comprises at least one material selected from a material group consisting of In, Sn, Al, Au, Pt, Zn, Ge, Ag, Ti, Pb, Pd, Cu, AuBe, AuGe, Ni, Cr, PbSn, AuZn, and indium tin oxide, or other substitute materials. The shape of the transparent patterned layer corresponds to at least one graph profile selected from a graph profile group consisting of semicircular, pyramidical, conical, or other substitute graph profiles. The first semiconductor stack layer comprises at least one material selected from a material group consisting of AlGalnP, AlInP, AlN, GaN, AlGaN, InGaN, and AlInGaN, or other substitute materials. The light-emitting layer comprises at least one material selected from a material group consisting of AlGalnP, GaN, InGaN, and AlInGaN, or other substitute materials. The second semiconductor stack layer comprises at least one material selected from a material group consisting of AlGaInP, AlInP, AlN, GaN, AlGaN, InGaN, and AlInGaN, or other substitute materials.

These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a prior art flip-chip light-emitting device.

FIG. 2 is a schematic diagram of a present invention flip-chip light-emitting device with a micro-reflector.

FIG. 3 is a schematic diagram of a present invention flip-chip light-emitting device with a micro-reflector.

FIG. 4 is a schematic diagram of a present invention flip-chip light-emitting device with a micro-reflector.

DETAILED DESCRIPTION

Please refer to FIG. 2, which is a schematic diagram of a flip-chip light-emitting device 1 with a micro-reflector. The light-emitting device 1 includes a transparent substrate 10, a first contact layer 11 having an upper surface divided as a first surface and a second surface formed over the transparent substrate 10, a first cladding layer 12 formed over the first surface, a light-emitting layer 13 formed over the first cladding layer 12, a second cladding layer 14 formed over the light-emitting layer 13, a micro-reflector formed over the second cladding layer 14, which including a second contact layer 15 and a reflective layer 16 formed over the second contact layer 15, a first electrode 17 formed over the second surface, and a second electrode 18 formed over the reflective layer 16 of the micro-reflector. The second contact layer 15 of the micro-reflector is a transparent patterned layer. The second contact layer 15 and the reflective layer 16 include patterns, and the shape of the second contact layer 15 and the reflective layer 16 correspond to a discontinuous or continuous distributed geometric graph profile.

Please refer to FIG. 3, which is a schematic diagram of a light-emitting device 2 with a micro-reflector. The light-emitting device 2 includes a transparent substrate 20, a first contact layer 21 having an upper surface divided as a first surface and a second surface on an upper surface formed over the transparent substrate 20, a micro-reflector including a transparent patterned light-emitting stack layer, an insulating layer 29, and a reflective layer 26 formed over the first surface of the first contact layer 21, a first electrode 27 formed over the second surface of the first contact layer 21, and a second electrode 28 formed over the reflective layer 26 of the micro-reflector. The transparent patterned light-emitting stack layer includes a first cladding layer 22 formed over the first surface of the first contact layer 21, a light-emitting layer 23 formed over the first cladding layer 22, a second cladding layer 24 formed over the light-emitting layer 23, and a second contact layer 25 formed over the second cladding layer 24. The insulating layer 29 forms over the transparent patterned light-emitting stack layer, and the reflective layer 26 forms over the insulating layer 29. There is an ohmic contact between the reflective layer 26 and the transparent patterned light-emitting stack layer. The shape of the transparent patterned light-emitting stack layer corresponds to a discontinuous or continuous distributed geometric graph profile.

Please refer to FIG. 4, which is a schematic diagram of a light-emitting device 3 with a micro-reflector. In light-emitting device 3, a chip is bonded onto a transparent substrate by means of direct pressure bonding or transparent adhesive layer bonding. The light-emitting device 3 includes a transparent bonding substrate 30, a bonding layer 300 formed over the transparent bonding substrate 30, a transparent conductive layer 32 with a first surface and a second surface formed over the bonding layer 300, a first contact layer 33 formed over the first surface, a first cladding layer 34 formed over the first contact layer 33, a light-emitting layer 35 formed over the first cladding layer 34, a second cladding layer 36 formed over the light-emitting layer 35, a micro-reflector including a second contact layer 37 and a reflective layer 38 formed over the second contact layer 37 formed over the second cladding layer 36, a first electrode 39 formed over the second surface, and a second electrode 40 formed over the reflective layer 38 of the micro-reflector. The second contact layer 37 of the micro-reflector is a transparent pattern layer. The bonding layer 300 can be formed from adhesive, semiconductor material, transparent oxide, or a transparent metal layer for bonding the substrate 30 to the first contact layer 33. A first reaction layer can be formed between the bonding layer and transparent bonding substrate, and a second reaction layer can be formed between the bonding layer and the transparent conductive layer 32.

In the above-mentioned three embodiments, a transparent conductive layer can be formed between the second electrode and the reflective layer. The shape of the transparent patterned corresponds to at least one graph profile selected from a graph profile group consisting of semicirclular, pyramidical, and conical, or other substitute graph profiles. The transparent substrate includes at least one material selected from a material group consisting of GaP, glass, SiC, GaN, ZnSe, and sapphire, or other substitute materials. The reflective layer includes at least one material selected from a material group consisting of In, Sn, Al, Au, Pt, Zn, Ge, Ag, Ti, Pb, Pd, Cu, AuBe, AuGe, Ni, Cr, PbSn, AuZn, and indium tin oxide, or other substitute materials. The transparent conductive layer includes at least one material selected from a material group consisting of indium tin oxide, cadmium tin oxide, antimony tin oxide, zinc oxide, zinc tin oxide, Be/Au, Ge/Au, and Ni/Au, or other substitute materials. The first cladding layer includes at least one material selected from a material group consisting of AlGaInP, AlInP, AlN, GaN, AlGaN, InGaN, AlInGaN, and ZnSe, or other substitute materials. The light-emitting layer includes at least one material selected from a material group consisting of AlGaInP, GaN, InGaN, AlInGaN, and ZnSe, or other substitute materials. The second cladding layer includes at least one material selected from a material group consisting of AlGaInP, AlInP, AlN, GaN, AlGaN, InGaN, AlInGaN, and ZnSe, or other substitute materials. The second contact layer includes at least one material selected from a material group consisting of GaP, GaAs, GaAsP, InGaP, AlGaInP, AlGaAs, GaN, InGaN, AlGaN, and ZnSe, or other substitute materials. The first contact layer includes at least one material selected from a material group consisting of GaP, GaAs, GaAsP, InGaP, AlGaInP, AlGaAs, GaN, InGaN, AlGaN, and ZnSe, or other substitute materials. The insulating layer includes at least one material selected from a material group consisting of SiNx and SiO2, or other substitute materials.

Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims. 

1. A flip-chip light-emitting device with a micro-reflector comprising: a substrate; a first semiconductor stack layer formed over the substrate; a light-emitting layer formed over the first semiconductor stack layer; a second semiconductor stack layer formed over the light-emitting layer; and a micro-reflector formed over the second semiconductor stack layer comprising a transparent patterned layer and a reflective layer formed over the transparent patterned layer.
 2. The flip-chip light-emitting device with a micro-reflector of claim 1 further comprising a transparent adhesive layer between the first semiconductor stack layer and the substrate.
 3. The flip-chip light-emitting device with a micro-reflector of claim 2 further comprising a first reaction layer between the transparent adhesive layer and the substrate.
 4. The flip-chip light-emitting device with a micro-reflector of claim 2 further comprising a second reaction layer between the transparent adhesive layer and the first semiconductor stack layer.
 5. The flip-chip light-emitting device with a micro-reflector of claim 4 further comprising a transparent conductive layer between the second reaction layer and the first semiconductor stack layer.
 6. The flip-chip light-emitting device with a micro-reflector of claim 2 further comprising a transparent conductive layer between the transparent adhesive layer and the first semiconductor stack layer.
 7. The flip-chip light-emitting device with a micro-reflector of claim 1 wherein the shape of the transparent patterned layer corresponds to a graph profile selected from a graph profile group consisting of semicircular, pyramidical, and conical.
 8. The flip-chip light-emitting device with a micro-reflector of claim 1 wherein the shape of the reflective layer corresponds to a graph profile selected from a graph profile group consisting of semicircular, pyramidical, and conical.
 9. The flip-chip light-emitting device with a micro-reflector of claim 1 wherein the shape of the transparent patterned layer corresponds to a discontinuous distributed geometric graph profile.
 10. The flip-chip light-emitting device with a micro-reflector of claim 1 wherein the reflective layer comprises a material selected from a material group consisting of Sn, Al, Au, Pt, Zn, Ag, Ti, Pb, Pd, Ge, Cu, AuBe, AuGe, Ni, PbSn, AuZn, and indium tin oxide.
 11. The flip-chip light-emitting device with a micro-reflector of claim 1 wherein the substrate is connected to the micro-reflector by direct wafer bonding. 